Ruger Holsters

I posted this in the Ruger gunsmithing section probably in error.
I do leatherwork and have orders for two custom holsters. Locally I have access to similar models but not the exact ones. Both holsters are to be basic cowboy type.
First, I'm working on a holster for a .44 Redhawk. The closest I can find locally is a .41 S&W. Can anyone tell me if the frame size is close enough for a decent fitting holster?
Second, another fellow wants one for a .44 Super Blackhawk. There's .44 Blackhawk locally that I can use for a pattern. As far as making a holster, is there enough difference to worry about?
I know this might not be the type of stuff for your forum but I figured go the people who know.
I run into this type of jam every so often.
Appreciate any help
STR